Exosomes from LNCaP cells promote osteoblast activity through miR-375 transfer

Previous studies have revealed that exosomes influence tumour metastasis, diagnosis and treatment. In addition, exosomal microRNAs (miRNAs/miRs) are closely associated with the metastatic microenvironment; however, the regulatory role of exosomal miRNAs from prostate cancer cells on bone metastasis remains poorly understood. In the present study, a series of experiments were performed to determine whether exosomal miR-375 from LNCaP cells promote osteoblast activity. Exosomes were isolated and purified by ultracentrifugation, total RNA from cells and total miRNA from exosomes were then extracted, and miR-375 levels were detected by reverse transcription-quantitative polymerase chain reaction. Exosome libraries from LNCaP and RWPE-1 cells were sequenced and selected using an Illumina HiSeq™ 2500 system. The effects of exosomes on osteoblasts were determined and osteoblast activity was evaluated by measuring the activity of alkaline phosphatase, the extent of extracellular matrix mineralisation and the expression of osteoblast activity-associated marker genes. Morphological observations, particle size analysis and molecular phenotyping confirmed that cell supernatants contained exosomes. Differential expression analysis confirmed high miR-375 expression levels in LNCaP cell-derived exosomes. The ability of exosomes to enter osteoblasts and increase their levels of miR-375 was further analysed. The results demonstrated that exosomal miR-375 significantly promoted osteoblast activity. In conclusion, the present study may lead to further investigation of the function role of exosomal miR-375 in the activation and differentiation of osteoblasts in PCa.